View 03 - Old (>25 years) Hughes HeNe internal mirror laser tube,
possibly a prototype. The output power would probably have been about 3 to 5
mW though I doubt it is still working. Approximate dimensions are 12" x 1.4".
Note all glass construction and electrical connections only at the anode-end
of the tube.

View 07 - Melles Griot style external mirror HeNe tube. This would
appear to be similar to the more conventional HeNe tubes above except that
instead of integral mirrors, it has Brewster windows. In addition, the
gas fill merits attention: He-3 and Ne-22 (the common helium isotope is He-4
and neon is Ne-20). So, the lasing wavelength is likely to be non-standard.

View 09 - Toshiba HeNe tube similar or identical to a model LG-3217. Note
all glass construction (non-adjustable mirrors) and internal Brewster window
to produce polarized beam. Both electrical connections exit from one. The
output beam dot and slight reflection from the internal Brewster window are
visible in this photo. This type of HeNe tube was used in some Sony
laserdisc players. See: "Assorted Laserdisc Player Components" in the
Photos of Miscellaneous Lasers, Components,
and Accessories wing for an example.

View 11 - Tube powered up with perfectly normal pinkish orange discharge.
The only way to tell it is a special tube is by the color of the output
(green!) and/or by the transmission of the mirrors (probably orange or red).
(Actually, due to a slightly different gas-fill ratio and likely the use
of istopically pure He and Ne (possibly He3 and Ne22), the color tends to
be a bit more pinkish than the typical red HeNe laser discharge.)

(The following photo provided courtesy of: Keith (kee@asu.edu).)

Here are three more 'other color' HeNe tubes. The top one is a Hughes style
yellow (594.5 nm) tube, the middle one is also supposed to be a yellow HeNe
laser tube but this sample produces some orange (604.6 nm) as well, and the
bottom one is a green (543.5 nm) tube which also has a built-in three-screw
mirror adjuster on its OC.

The following two photos are of a HeNe tube and power supply (or what's left
of the power supply) probably from a HeNe laser based laser pointer. I just
couldn't resist buying this on Ebay! The tube in the photos below is actually
being powered from a separate supply - the seller made no claims as to the
functionality of what is visible. And, for good reason as it was dead when
I got it. I have since cleaned up the HeNe tube good as new and repaired
the power supply. See the Laser FAQ section:
HeNe Laser Power Supply from HeNe Laser
Pointer (IC-HI3) for a complete schematic and more detailed description
of my experiences with this power supply, circuit operation, and its repair.

View 13 - Cute little Melles Griot HeNe laser tube (similar to model
05-LHR-122) and power supply clump. The inverter is on the left and the
thing that looks like a black end-cap is actually its PWM controller
conformal coated with rubber to keep out the curious. The HeNe tube puts
out about 1.1 mW.

View 14 - Closeup of inverter portion of HeNe laser pointer laser power
supply. Note how LARGE the main filter caps (part of the voltage doubler)
look in this photo. :) They are actually quite LARGE!

View 01 - Overall view of demonstration HeNe laser. The
HeNe tube and ballast resistor (!!) are clearly visible. The circuit board
on the right appears to be the AC-DC power supply that feeds the actual HeNe
laser power supply which is barely visible on the lower deck.

Bell Labs developed and produced some number and variety of portable
demonstrators to promote the idea of optical communications. At least
some of these had an actual working HeNe laser based on a two-Brewster
laser tube with external mirrors in adjustable
mounts, and power supply in a self-contained unit with orange Plexiglas
cover over the tube. Some included a modulator with a separate receiver
based on a solar cell. These demonstrators came packed in a
handy traveling salesman's type sample case. :)

I don't know for sure if all of these had working lasers. (The one in
the next section is definitely fake, but could easily fool a non-laser
geek type.) But, now I do have the remains of one of
the laser-only units, so that confirms the presence of real lasers in
at least some models. The tube is broken but it indeed was a complete
working HeNe laser at one time. The external mirrors look pristine, which is
probably just as well since they are likely soft-coated and cannot be
cleaned. The mirror mounts are, well, funky. The mirrors are attached to a
spring flexure with three screws with tapered ends (user accessible!)
entering from the mount's edge at the 12, 4, and 8 o'clock positions.
I have little doubt that if I mounted almost any two-Brewster HeNe laser
tube between the mirrors, it would lase. I may do just that someday,
at least as a test. Of course, if someone wanted to donate or build a
an historically authentic HeNe laser tube to go in there, that would
be even better. :) I couldn't find any dates on the unit but it must be
quite old.

The power supply for the HeNe laser tube is very simple - just a high
voltage transformer (about 3,000 VRMS) feeding a bridge rectifier
consisting of 4 series pairs of 426J-263 diodes (whatever they are) with a
single 0.1 uF, 4 kV capacitor and a series pair of 4.64M ohm bleeder
resistors across its output. The ballast is a 75K ohm 25 W resistor
and there is a current meter in the negative return. Although it reads
50 mA full scale, the ballast resistor would have turned to smoke long
before this current was reached - just over 18 mA would result in
25 W dissipation in the resistor. Given the relatively small diameter
of the bore (about 2 mm), 10 or 15 mA would probably be the normal
operating current. Since there is no adjustment for tube current, it's
not clear why a meter is needed at all. If the tube lights up, it's
operating correctly, go fiddle with the mirror adjustments if there is
no laser beam! :) The 0.1 uF capacitor doesn't really provide much
smoothing, so the result is closer to pulsed DC at 120 Hz. Thus the
tube must restart on every half cycle. (There is a wire wrapped around
the bore connected to the positive lead, presumably to help this.
Here's the circuit diagram:

The primary-side components not shown consist of the fuse, power switch, and
power indicator neon lamp.

Note that there is no actual indication on the thing I have that it is from
Bell Labs so I'm making an assumption based on its similarity to the one
below.

When I first acquired the photos of the demonstrator in the Gallery, I had
doubts as to whether it actually had a working laser or just a cool-looking
neon sign-type tube for show - and actually did the communications with a
separate conventional modulated lamp (an arc lamp is mentioned in the
description below and its presence doesn't make much sense otherwise).
The ends of the tube are not clear in any of the photos and the bore
looks too wide to be part of a functional HeNe laser tube. In addition,
the mirrors look suspiciously clear but perhaps they are just missing
on this unit. But the access holes in the Plexiglas cover for adjusting
the mirrors that are present on mine are not visible on this one.

However, for what follows, I have to assume it is a real laser - else I
couldn't have included it in the "Assorted Helium-Neon Lasers" wing of
the gallery! :)

(These 8 photos and the following description (the three paragraphs) provided
courtesy of: Rick Carpenter (Fiesta1043@aol.com).)

This is a true collectors' item. It is a laser beam demonstrator kit used to
show the future of communications via laser optics. Here is the story. This
unit was rescued from the trash years ago at a Southern Bell office by my
brother in law who is a retired telecommunications engineer for the phone
company. This unit was used in community relations programs as a demonstrator
unit to show how telephone signals could travel over laser light. We believe
it is vintage 60's judging form the tube circuits and the original carrying
case.

The unit measures 20" long and has an amber colored Plexiglas cover over the
laser tube. The only markings are 3 kV which resembles some of the vintage
Western Electric stamps. At one end is access to a concentrated arc lamp,
(Sylvania A2/T, a spare one is included in the case, just in case). The
telephone hand set was plugged into the unit and the receiver of the beam is
the small black cylindrical object seen in the photos. In the cylinder is a
photocell like surface with wires that would probably connect to an amplifier
and telephone receiver to get the signals on the other end.

The demonstrator is packed in a Salesman's sample-like carrying case
(genuine fiberboard construction!) along with 4 spare vacuum tubes (for
the modulater?), fuses, telephone handset, and the optical receiver.

View 02 - View with amber Plexiglas cover removed. The HeNe tube
(if that's what it is) construction is ancient. Note that while the color
of the discharge in tube bore appears yellow, according to Rick, it is
actually red (amazing what digital cameras will do!). The red color,
indicates, not surprisingly, that the tube is gassy and would need
to be refilled. It's amazing that there is any gas left after 30 or more
years! (This actually lends credibility to the idea it is actually a neon
sign tube which would have been hard-sealed even in those days - HeNe laser
tubes were of soft-seal construction until much later.) In any
case, replacement isn't really an option as it wouldn't look nearly as cool!
Better to have it glow the wrong color and not lase, than to have some modern
barcode scanner tube in its place. :)

View 03 - Demonstrator with accessories. The black thing that looks a
a bit like a caulking gun is the optical receiver.

View 07 - Interior of electronics chassis showing arc lamp
and power transformer. I don't know what purpose the lamp serves other
than possibly to aim the device (the lamp holder is on a mount that could be
adjusted for optimal focus or collimation). (Or, as noted, that it
actually produces the communications beam and there is no laser involved.)

This one is definitely fake, but could make a decent prop for a futuristic
movie (at least in the 1960s). It consists of a neon sign-type tube with red
coated glass mounted in a nicely machined aluminum assembly that might have
been for a real laser at some point. At one end is a tiny
incandescent flashlight lamp - no LEDs in those days! The modern version
would use a diode laser module! A red plastic filter
and glass lens produces a reasonable facsimile of a poorly collimated beam.
But as you'll see in the photo of the unit in operation, it sort of looks
like a laser beam spot. There is also a pair of glass lenses at other
end that appear to serve no useful purpose other than filling the holes
in the aluminum structure, which for some inexplicable reason, is cut away.

The neon tube could probably run on a HeNe laser power supply (though
not very brightly), but I found a small neon sign transformer (3500 V)
that works fine. It glows a gorgeous deep red for which the digital photo
does not do justice. The beam bulb runs on 3 V.

It is not known whether this is a one-of-a-kind or was replicated like
the traveling salemans' laser demonstrator kit.

This is a set of older Aerotech self contained HeNe lasers, probably around
2 to 3 mW (by the size and model number, despite what the CDRH sticker says
about Class IIIb and 25 mW max!). They date from 1980 and thus
I am impressed that they work at all. However, apparently after a few minutes,
they start flickering indicating a tube pressure problem (probably high from
leakage of the soft-seal mirrors).

Dr. Narinder Kapany founded Optics Technology, Inc. in 1960 and was
Chairman of the Board, President, and Director of Research until
1972. The company made lasers and fiber optic assemblies for a wide
range of specialties, and is still in business. One of Dr. Kapany's
hobbies is sculpture, which may explain the extravagant industrial
design which went into the case of the Model 170 laser.

I was going to list this with the statement "Cutting Edge Technology" until I
realized the pun. This was a true state of the art piece of equipment from the
early 1970's. It came from the estate of a NASA engineer. It was made by
Optics Technology Inc., out of Palo Alto, California.

I wasn't sure of exactly what I had, but luckily I live down the street from a
high tech laser company whose engineers were more than happy to take a look at
this. Once they had the top off, this drew them like bees to honey! This laser
has an elaborate glass tube with Epoxy seals and of course, after all this
time, the gasses have all leaked out/air has leaked in, whatever. The
engineers thought it may have generated a 3 mW beam and showed me the
present day equivalent, which was about the size of a very long pencil. They
finally proclaimed this as an extremely interesting relic!

This is a vintage external mirror HeNe laser with a relatively wide bore and a
heated filament-cathode. The Americal Optical Corporation model 3100 HeNe
laser is probably made by Gaertner as their name also appears on the sample
I have. The AO-3100 is (described in the chapter:
Helium-Neon Lasers of Sam's Laser FAQ
(section: "A Really Old HeNe Laser").

View 01 - Montage showing the exterior and interior of laser. The two
side-arms contain the cathode which is a heated tungsten coil filament and
the anode which is just the getter support wire and the getter itself.

These 7 photos are of a working sample I now have.
It was contributed by Phil Bergeron at the
USF Physics lecture - Demonstration Facility, Tampa, FL. Thanks Phil! :)

The color rendition of my digital camera isn't very good.
The color in the main bore and larger sections of tubing actual should look
close to that in normal HeNe lasers. But the cathode glow (the bright blob)
is actually more yellow (though not qutie the yellow in these photos). :)

(The following seven photos and description provided courtesy of
kepsalesantiques.)

The Electro Optics Associates (EOA) Model LAS-101 was intended for
the educational market. It is a portable laser designed for use with a
user-provided power supply, and it features a double-walled plasma
tube for extended lifetime, an internal resonator structure and a
stylish green Plexiglas cover. EOA was a Palo Alto, Calif.-based
company that dissolved in the mid-1970s.

Specifications:

Model: LAS-101

Technology Type: Helium-Neon Gas Laser

Output: 0.5mW single mode

Power Supply Input: 300VDC 60mA

Dimensions: 15 1/2" W x 6" H x 4 3/4" D

Weight: 4 lbs

The EOA model LAS-101 included a booklet called "Laboratory Experiments
with Coherent Light" to help science educators explain the new
technology to students.

This is an example of a very early Helium-Neon gas laser built for
portability and general lab use. The laser was powered by a
user-supplied 300VDC 60mA lab power supply, gave 0.5 mW single mode,
and cost $660 new.